Mustela putorius fuo

Commonly sold in pet stores across the United States and other countries, this ferret is descended from the European polecat. They are generally friendly animals that can make good pets. Domestic ferrets tend to be slightly larger than black-footed ferrets. They are found in a variety of colors, from albino to dark sable, but lack the solid black mask, feet, and tip of tail. Instead, they tend to have grey or brown masks and feet. Domestic ferrets also have longer fur than black-footed ferrets.

Mustela putorius

This polecat is very similar in appearance to the domestic ferret, but does not have as much variation in color. They are usually dark sable with a dark brown mask. They are native to Europe and the northern part of Morocco, although absent from Ireland. There are many subspecies of the European polecat.

Mustela eversmanii

The Siberian polecat is the closest genetic relative of the black-footed ferret. They closely resemble the European polecat, but tend to be a little lighter in color. They inhabit the steppes and sub-deserts of Eastern Europe, republics of the former USSR, Mongolia and parts of China.

Mustela frenata

The bridled weasel is smaller in size than the black-footed ferret. They have brown fur on the upper part of their bodies, and white to yellow fur on the undersides. Like black-footed ferrets, they have black-tipped tails, but they lack the black feet and solid black mask. Some variations can have a white mask, or no mask and a mostly black face. In the northern parts of their range, they turn white in the winter. Bridled weasels inhabit forests, thickets, and farmland throughout the United States except parts of southeast California, Nevada and Arizona. They are also found in Canada, Mexico and South America.

Mustela erminea

The ermine is very similar in appearance to the bridled weasel, but it is slightly smaller with a shorter tail. They also turn white in winter. Ermines are found across the northern half of the United States, throughout Canada, Alaska and Greenland, and in Eurasia. They inhabit mostly forests and farmlands.

Neovison vison, formerly Mustela vison

Mink are about the same size as black-footed ferrets. They are a solid dark brown color with no mask, black-tipped tail, or black feet. Some have white chins and muzzles. Mink inhabit wetlands, freshwater swamps, riverbanks and shorelines across most of Canada and the United States, except the desert southwest and the northern tundra.

Martes americana

The American marten is much larger than the black-footed ferret. They are arboreal animals (live mainly in trees). They have thick, brown fur with a yellow to orange chest and throat. They also have bushy tails. Martens inhabit forested and mountainous areas. They are found throughout Canada and Alaska, and in parts of the United States including the Rocky Mountains, Great Lakes region and New England.